Distillation, formaldehyde solutions Steam

In a 500 ml. three-necked flask, fitted with a reflux condenser and mechanical stirrer, place 121 g. (126-5 ml.) of dimethylaniline, 45 g. of 40 per cent, formaldehyde solution and 0 -5 g. of sulphanilic acid. Heat the mixture under reflux with vigorous stirring for 8 hours. No visible change in the reaction mixture occurs. After 8 hours, remove a test portion of the pale yellow emulsion with a pipette or dropper and allow it to cool. The oil should solidify completely and upon boiling it should not smell appreciably of dimethylaniline if this is not the case, heat for a longer period. When the reaction is complete, steam distil (Fig. II, 41, i) the mixture until no more formaldehyde and dimethylaniline passes over only a few drops of dimethylaniline should distil. As soon as the distillate is free from dimethylaniline, pour the residue into excess of cold water when the base immediately solidifies. Decant the water and wash the crystalline solid thoroughly with water to remove the residual formaldehyde. Finally melt the solid under water and allow it to solidify. A hard yellowish-white crystalline cake of crude base, m,p. 80-90°, is obtained in almost quantitative yield. RecrystaUise from 250 ml. of alcohol the recovery of pure pp -tetramethyldiaminodiphenylmethane, m.p. 89-90°, is about 90 per cent. 

To 500 g. (3.85 moles) of freshly distilled ethyl acetoacetate in a i-l. flask set in ice and well cooled, are added 152 g. (2.0 moles) of 40 per cent aqueous formaldehyde solution and 20-25 drops of diethylamine. The flask and contents are kept cold for six hours and are then allowed to stand at room temperature for forty to forty-five hours. At the end of this time two layers are present, a lower oily layer and an upper aqueous layer. The layers are separated, and the aqueous layer is extracted with 50 cc. of ether. The ether solution is added to the oily layer, and the resulting solution is dried over 30 g. of calcium chloride. The ether is then removed by distillation on a steam bath. The residue, amounting to approximately 500 g., is diluted with an equal volume of alcohol and is thoroughly cooled in an ice bath. Ammonia is then passed into the mixture until the solution is saturated. This requires from four to eight hours, and during this time the flask is kept packed in ice. The ammoniacal alcoholic solution is allowed to stand at room temperature for forty to forty-five hours. Most of the alcohol is now evaporated the residue is cooled, and the solid i,4-dihydro-3,5-dicarbethoxy-2,6-dimethylpyridine is removed from the remaining alcohol on a suction filter. The dried ester melts at 175-180 and amounts to 4ro-435 g. (84-89 per cent of the theoretical amount). 

To 217 grams (0.456 mol) of N,N -bis[1-methyl-3-(2,2,6-trimethylcyclohexyl)propyll-I.B-hexanediamine were added 182 ml (3.04 mols) of formic acid (90%). The resulting colorless solution was cooled, then 91.3 ml (1.043 mols) of formaldehyde (37%) were added. The solution was heated at steam temperature with occasional shaking for 2 hours and then refluxed for 8 hours. The volatiles were distilled off at steam temperature under water vacuum and the residual oil was made strongly alkaline with 50% potassium hydroxide. 

Methylation of aliphatic amines to tertiary amines 1015 1 mole of a primary amine is added with cooling to a mixture of 5 moles of 90 % formic acid and 2.2 moles of 35 % formaldehyde solution. Secondary amines require only half of these amounts of formic acid and formaldehyde, but an excess is not disadvantageous. Reaction begins when the mixture is heated on a steam-bath. When the initial vigorous evolution of carbon dioxide ceases, the mixture must be heated for a further 2-4 h, in all for 8-12 h. Then somewhat more than 1 mole of hydrochloric acid is added and the formic acid and formaldehyde are distilled off. The colorless residue is dissolved in water and basified with 25 % sodium hydroxide solution, and the amine is distilled off in steam. The distillate is saturated with solid potassium hydroxide, and the oil that separates is dried over potassium hydroxide and distilled from sodium. The following tertiary amines were thus obtained in more than 80% yield iV,iV-dimethylbutyl-amine, b.p. 94° A TV-dimethylbenzylamine, b.p. 176-180° and 1-methylpiperidine, b.p. 106°. 

Liberation of methanol during decomposition of 1-methoxy-heptyl-l-hydroperoxide was demonstrated by holding a hot copper wire in the vapor. The odor of formaldehyde was detected. From the solution, the oxime of heptaldehyde was obtained (m.p., 54-55.5°C.) undepressed in admixture with an authentic sample. (Found C, 65.16 H, 11.55 N, 10.83%. C7Hi5ON requires C, 65.07 H, 11.70 N, 10.84%.) Another sample of the hydroperoxide (0.73 gram) was boiled for a few minutes with dilute H2S04. The solution was cooled, excess of sodium hydroxide was added, and the mixture was boiled under reflux for 1.5 hours, then acidified and steam-distilled. The ether extract of the distillate was separated into neutral and acid (0.071-gram) fractions. From the latter, the amide of heptoic acid (m.p. 92-94°C.) was obtained. 

In a 5-I. round-bottom flask fitted with a stopper holding a condenser set for downward distillation and a thermometer which will extend well into the liquid, are placed 4000 g. of technical formaldehyde (35-40 per cent sp. gr. 1.078 at 20°) and 2000 g. of technical ammonium chloride. The mixture is heated on the steam bath until no more distillate comes over and then over a flame until the temperature of the solution reaches 104°. The temperature is held at this point until no more distillate comes over (four to six hours). The distillate, which consists of methylal, methyl formate and water, may be treated as described in Note 3,... 

A portion of the reaction solution was acidified with sulfuric acid and steam-distilled into sodium hydroxide solution. The distillate was found to contain formaldehyde and formic acid. The formaldehyde was identified by precipitation with dimedone (31). The precipitate had a melting point of 186.0-86.5° C. as... 

The formaldehyde in a 5.00-g sample of a seed disinfectant was steam distilled, and the aqueous distillate was collected in a 500-mL volumetric flask. After dilution to volume, a 25.0-mL aliquot was treated with 30.0 mL of 0.121 M KCN solution to convert the formaldehyde to potassium cyanohydrin. 

Ingles heated a solution of n-glucose, sodium sulfite, and bisulfite, removed the cations, and steam-distilled the residue. The product, free of carbonyl-bisulfite addition compounds, was chromatographed on an ion-exchange resin, giving a sulfonic acid. This acid yields a crystalline brucine salt and phenyl- and (2,4-dinitrophenyl)-osazones. The osazones consume 1 mole of periodate per mole, liberating 1 mole of formaldehyde but no formic acid. The (2,4-dinitrophenyl)osazone also forms a diacetate. The acid is oxidized by sodium hypoiodite, taking up 1 mole of oxidant per mole. From these reactions and the possible reaction mechanisms for its formation, structure (41), a 3,4-dideoxy-4-sulfo-n-hexosulose, was proposed for the sulfonic acid. ... 

A. Hydroxymelhylimidazole picrate. To 222 g. (1 mole) of basic cupric carbonate (Note 1) in a 5-1. flask are added 1.5 1. of distilled water and 720 g. (800 ml., 12 moles) of 28% ammonia. The bulk of the copper carbonate is brought into solution by swirling 112 g. (100 ml., 1.3-1.4 moles) of 37-40% formaldehyde and 90 g. (0.475 mole) of commercial 95% fructose are added. The solution is well mixed and placed on a steam bath... 

A mixture of 17.5 gm (0.1 mole) of 2-(/>-tolyl)piperidine, 30 gm (0.59 mole) of 90% formic acid, and 25 gm (0.24 mole) of 35% formaldehyde is heated under reflux for 12 hr on a steam bath. The reaction mixture is cooled and 15 ml of concentrated hydrochloric acid is added. Heating under reflux is then continued for another 5 hr. Then the reaction mixture is cooled, made strongly basic with sodium hydroxide solution, and extracted with benzene. The benzene extract is dried over anhydrous sodium or potassium hydroxide. The benzene solution is then distilled. After removal of the solvent, the product distills at 117°-118°C (6 mm). Yield 17.8 gm (94%). 

The characteristic reactions of formaldehyde with phenolic componnds and amines have also been adapted to the detection of the aldehyde in food-.stuffs. In such instances the material i generally steam-distilled and a qualitative analysis is then carried out on the distillate obtained. Cohn -shakes 2 ec of the distillate with an equal volume of 0.1 per cent resorcinol solution, then carefully adds 2 ce of concentrated sulfuric acid to produce a dense precipitate at the zone of contact between acid and solution with a dark violet-red zone immediate v below. Fomiic, ox alic, and tartaric acids are claimed not to interfere with this color reaction, which is sensitive to OjOO(K>5 mg foimaldehi de. Gallic acid reacts with like sensitivity to form an emerald green bandb The test devi.Sed by Pittarelli (page 247) is reported to be of value for the detection of formaldehyde in wine, milk. 

The distillation procedure described in connection t 4th the isolation of jormaldeh de for purposes of detection may also be employed for the quantitative isolation, of formaldehyde for analysis. Formaldehyde can be quantitath eh remo ed iroru aqueous solutions containing less than 10 per cent CHaO distillation or preferably by steam distillation. This treatment also h> drolyzes loose compounds of formaldehyde in many instances so that the combined formaldehyde can be isolated quantitativel3 ... 

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